Glastonbury Festival-goers should be able to charge their mobile phones using
nothing more than a T-shirt, although may have to risk permanent hearing
damage to do so.

Orange, the mobile phone company, have produced a T-shirt which can use the noise of the festival music to charge their phones. The charging system is based on "piezoelectric film", a technology commonly used in hi-fi speakers, which turns vibrations - like sound waves - into electrical voltage, and is thin enough to be woven into a cotton shirt.

The energy gathered from sound waves is stored in a reservoir battery, which can then be plugged into a mobile phone to charge it. The Orange engineers said they chose a T-shirt because it is an everyday item that people will have on them, and because it has a large surface area which can receive a lot of sound waves.

Unfortunately, despite this, the amount of energy gained is not huge. According to Orange, "over the course of the weekend" the shirt could store as much as six watt hours - which, as the technology website The Register points out, "should be enough to recharge a smartphone, once, if you're lucky". And standing next to a speaker for hours at a time to charge your phone is unlikely to be good for your aural health. But it may allow for a few extra hours' battery life if used wisely.

For last year's festival, Orange produced wellington boots with chargers in the heel, which gained energy from walking movement; the year before they made small, portable windmills for generating electrical power. They have hinted that all three items may become saleable products.